Tennessee Code Title 66. Property § 66-26-110

(a) Any instruments so proved or acknowledged, certified and registered, shall be received as evidence in any of the courts, judicial and administrative tribunals of the state, subject, nevertheless, to be impeached and proved to be a forgery, or to be otherwise inoperative, if the fact be so.

(b) In an action with respect to an instrument, the authenticity of and authority to make each signature on the instrument is admitted, unless specifically denied in the pleadings. If the validity of a signature is denied in the pleadings, and if the instrument is not registered or is not properly acknowledged or proved, the burden of establishing validity is on the person claiming validity, but the signature is presumed to be authentic and authorized, unless:

(c) Under the presumption set forth in subsection (b), the trier of fact must find that the signature is authentic and authorized, unless evidence to the contrary is introduced.